CZ117394A3 - Cement manufacturing process - Google Patents

Abstract

A method for manufacturing cement is described, by which gypsum is added to the clinker in the clinker cooler (3). Hereby it is obtained that the gypsum is dried in a safe, simple and inexpensive manner without substantial additional costs for establishment and operation.

Description

Technical field ¹

The invention relates to a method for producing cement.

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BACKGROUND OF THE INVENTION

Until now, it has been common practice in cement production to mix finely ground and cooled clinker material with gypsum and possibly other additives and then finely ground in a grinding machine.

Typically, the gypsum added contains water that needs to be removed to prevent cement solidification and hardening, and in the milling equipment containing the tube mill, dehydration and drying of the gypsum often occurs in a mill in which the temperature is relatively high.

However, tube mills are relatively energy intensive and currently there is a tendency to use roll mills instead of tube mills for grinding cement due to their higher efficiency.

However, the temperature of the roller mills is rarely high enough to achieve sufficient drying of the added gypsum, which has a negative effect on the properties of the cement.

This problem was solved by adding gypsum which was dehydrated prior to the addition in a separate drying device, which however increases the initial cost as well as the overall manufacturing cost.

Another suggested solution to the problem is to heat the material during grinding with a gas from a heat generator or with excess air from a clinker cooler, but the retention time in a roller mill, for example, is very short and the possibilities of achieving sufficient gypsum drying are very

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SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a process for the production of cement in which the abovementioned drawbacks of the known processes are overcome.

SUMMARY OF THE INVENTION

According to the invention, this object is achieved by a method of the kind mentioned at the outset, which consists in that at least part of the gypsum required for the production of cement is added to the clinker in the clinker cooler.

Thus, the gypsum can be dehydrated and dried in a simple manner by means of the heated air obtained from the cooling of the clinker, which is usually directed directly into the atmosphere, inter alia, through a filter. By allowing the gypsum and cooler fill point to be varied, the gypsum retention time in the cooler can be further adapted to both fine and coarse types of gypsum, so that they can be dried and dehydrated without prior grinding.

Thus, with the method according to the invention, in relation to processes using dehydration and drying in a current grinding plant or in a separate drying plant, the gypsum is dried in a safe, simple and inexpensive manner without substantial additional equipment and operating costs.

The mixture of clinker and gypsum is conveyed from the clinker cooler to the grinding machine, where the cemetary is finely ground. In order to be able to produce different types of cement containing different amounts of gypsum, it is preferred that the amount of gypsum filled into the cooler is less than or equal to the smallest amount of gypsum required in the finished cement. Subsequently, any fine adjustment of the percentage of gypsum can be carried out in the usual manner by adding the gypsum during fine grinding.

Depending on the desired degree of gypsum dehydration, the gypsum temperature and retention time in the clinker cooler can be controlled to the desired degree of dehydration by filling the gypsum in the clinker cooler in one or more different positions in the longitudinal direction of the cooler.

In order to reduce the amount of gypsum dust that can enter the cement kiln and / or preheater and firing kiln together with the cooling air, it is preferred that the gypsum is fed to the last section of the clinker cooler.

However, it cannot be completely excluded that part of the gypsum dust is entrained in the cooling air from the clinker cooler and it is therefore advantageous for the cooling air containing its gypsum dust to pass to a separator in which the gypsum dust separates from the air and returns to the clinker mixture. gypsum downstream of the clinker cooler.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in more detail in the following description by way of example with reference to the accompanying drawing, showing a diagram of a part of a cement production plant in which the method according to the invention can be carried out.

DETAILED DESCRIPTION OF THE INVENTION

The apparatus comprises a rotary kiln 1, a clinker cooler 3 with outlet 4 and an air duct 5 for supplying hot air from the clinker cooler 3 to a preheater (not shown). The clinker material leaving the clinker cooler 2 through the outlet 4 falls onto the conveyor 7 conveying the material to the roller press 9.

In the illustrated device, the gypsum can be filled into the clinker cooler 3 at the filling points 11 distributed along the longitudinal direction of the clinker cooler.

The clinker cooler 2 may comprise a screen 12 which changes the air flow from the last clinker cooler section 13 towards the furnace 1. The air from the last clinker cooler section may therefore, with its gypsum dust content, pass through a separate duct 15 to a separator 17 which may be for example, a cyclone separator, bag filter or electrostatic precipitator, from which the separated dust is returned via line 19 to a clinker / gypsum mixture, for example to a conveyor belt 7.

When the gypsum is fed to the clinker cooler 3 as proposed according to the invention, the gypsum is dehydrated and dried during its transport by the cooler along with the hot creamy material and any additional gypsum can be added to adjust the percentage of gypsum from the gypsum reservoir 21 via line 23.

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Claims (5)

PATENT CLAIMS Method for producing cement in an apparatus comprising a clinker cooler, characterized in that at least a portion of the gypsum required for the production of cement is added to the clinker in the cooling (3) clinker. Method according to claim 1, characterized in that the amount of gypsum fed into the clinker cooler (3) is less than or equal to the smallest amount of gypsum required in the finished cement. Method according to claim 1 or 2, characterized in that the gypsum is fed into the clinker cooler (3) in one or more positions (11) along the longitudinal direction of the cooler. Method according to claim 1, 2 or 3, characterized in that the gypsum is fed into the last clinker cooler section (13). Method according to any one of claims 1 to 4, characterized in that the cooling air from the last gypsum cooler section (13) containing the gypsum dust is passed to a separator (17) in which the gypsum dust is separated from the air and returned to the mixture. clinker and gypsum at some point behind the clinker cooler (3).